Date File Created Name of Creator 3/3/2009 Sheryl Singerling GeoRef Data 2006-091383 DN GeoRef TI "Time scales of pluton construction at differing crustal levels;examples from the Mount Stuart and Tenpeak Intrusions, north Cascades,Washington" AU "Matzel, Jennifer E P; Bowring, Samuel A; Miller, Robert B" AF "Massachusetts Institute of Technology, Department of Earth,Atmospheric, and Planetary Sciences, Cambridge, MA, United States(USA)" AF "San Jose State University, United States (USA)" SO "Geological Society of America Bulletin, vol.118, no.11-12,pp.1412-1430, Dec 2006" IS 0016-7606 CD BUGMAF PB "Geological Society of America (GSA), Boulder, CO, United States (USA)" DE absolute age; batholiths; Cascade Range; Cenozoic; Chiwaukum Schist;continental crust; crust; dates; emplacement; granodiorites; igneousrocks; Ingalls Complex; intrusions; island arcs; Jurassic;lithostratigraphy; magma chambers; magmas; magmatism; Mesozoic;models; Mount Stuart; Napeequa Complex; Nason Ridge Gneiss; Neogene;nesosilicates; orthosilicates; P-T conditions; Pliocene; plutonicrocks; processes; silicates; Swakane Gneiss; Tenpeak Pluton; Tertiary;U/Pb; United States; Washington; zircon; zircon group AB "Deciphering the magmatic history of continental magmatic arcs, ingeneral, and the growth history of individual intrusions, inparticular, is key to understanding the complex history of magmageneration, segregation, and transport that define the dynamics ofcrustal growth. We utilize high precision U-Pb geochronology toresolve a detailed magmatic history from two composite intrusions, the2-4 kbar Mount Stuart Batholith and the 7-10 kbar Tenpeak Pluton,emplaced in the Cretaceous North Cascades Arc. This temporal frameworkprovides a way to evaluate models of pluton growth that explain commonfeatures of intrusions such as concentric compositional zoning andinternal magmatic contacts. U-Pb zircon crystallization ages wereobtained from 12 samples of the Mount Stuart Batholith and 8 samplesof the Tenpeak Intrusion, representing the range of compositionaldiversity and geographical extent. These dates indicate that the MountStuart Batholith was constructed over a approximately 5.5 m.y. timeperiod that was punctuated by four intervals of high magma flux. Thedurations of the high-flux periods are short (a few hundred thousandyears) relative to the duration of the batholith. The consistentpattern of magmatic fabrics and the lack of distinct contacts in thebatholith may be explained by the juxtaposition of melt-rich and mushzones with subtle contacts between mineralogically and texturallysimilar tonalite and time-transgressive magma fabrics.In contrast, theTenpeak Intrusion was constructed over a approximately 2.6 m.y. timeperiod, with magma influx distributed throughout the intrusive historyand texturally distinct magma bodies. The Tenpeak Intrusion lacksdistinct age domains, which suggests that any magma reservoir wassmaller in size and potentially more ephemeral. Although the distinctage domains and discrete compositional and textural phases indicatethat pluton growth occurred incrementally, neither pluton bearsresemblance to a purely end-member incremental growth model whereby apluton is constructed from hundreds to thousands of discrete magmapulses that have little, if any, interaction. In particular, ages fromthe youngest domain of the Mount Stuart Batholith indicate that amelt-rich magma reservoir of > or =520 km (super 3) existed over a170 + or - 90 k.y. time span." LA English NT With GSA Repository Item 2006220 FE "References: 102; illus. incl. 2 tables, geol. sketch maps" PY 2006 PT Serial; Analytic CP United States (USA) LL "Latitude:N474500,N481500 Longitude:W1205500,W1211000" CL 05A Igneous and metamorphic petrology; 03 Geochronology CY "GeoRef, Copyright 2007, American Geological Institute. Referenceincludes data supplied by the Geological Society of America, Boulder,CO, United States" UD 200624 DO 10.1130/B25923.1 AN 2006-091383 JV 118 JI 12-Nov JP 1412-1430 Sample Data Item Age Max_age Min_age LatDD LongDD Loc_prec Location_Name Rock_Class Rock_Type Unit Collected_by Material State Units Ma Ma Ma DD DD Method 1 1 1 2 2 Sample Name MS26 96.27 96.37 96.17 47.6787 -120.8852 0.01 Mount Stuart batholith tonalite plutonic Matzel and others whole rock Washington MS17C 95.88 95.91 95.85 47.5763 -120.5889 0.01 Mount Stuart batholith diorite plutonic Big Jim Complex Matzel and others whole rock Washington MS5 95.87 95.9 95.84 47.7572 -120.8512 0.01 Mount Stuart batholith tonalite plutonic Matzel and others whole rock Washington MS6 95.44 85.49 95.39 47.8012 -120.913 0.01 Mount Stuart batholith granodiorite plutonic Matzel and others whole rock Washington JR-1 94.72 94.87 94.57 47.4312 -120.6848 0.01 Mount Stuart batholith tonalite plutonic Ingalls Complex Matzel and others whole rock Washington PC-F 94.25 94.39 94.11 47.4226 -120.614 0.01 Mount Stuart batholith tonalite plutonic Matzel and others whole rock Washington MS24 92.67 92.73 92.61 47.5533 -120.6497 0.01 Mount Stuart batholith tonalite plutonic Matzel and others whole rock Washington MS37 92.59 92.73 92.45 47.5945 -120.7899 0.01 Mount Stuart batholith tonalite plutonic Matzel and others whole rock Washington MS4 90.92 90.97 90.87 47.4911 -120.4601 0.01 Mount Stuart batholith gabbro plutonic Matzel and others whole rock Washington MS2 90.79 90.83 90.75 47.479 -120.5719 0.01 Mount Stuart batholith gabbro plutonic Matzel and others whole rock Washington MS13 90.78 90.86 90.7 47.3426 -120.6146 0.01 Mount Stuart batholith granodiorite plutonic Matzel and others whole rock Washington MS31 90.75 90.82 90.68 47.4256 -120.454 0.01 Mount Stuart batholith tonalite plutonic Matzel and others whole rock Washington TP31 93.1 94.2 92 48.0209 -120.9378 0.01 Tenpeak pluton tonalite plutonic White Mountain lobe Matzel and others whole rock Washington TP11 92.27 92.36 92.18 47.972 -120.8751 0.01 Tenpeak pluton tonalite plutonic Schaefer Lake phase Matzel and others whole rock Washington TP30 92.22 92.39 92.05 48.0251 -120.9374 0.01 Tenpeak pluton diorite plutonic Schaefer Lake phase Matzel and others whole rock Washington TP20 92.07 92.11 92.03 47.9615 -120.9498 0.01 Tenpeak pluton tonalite plutonic Schaefer Lake phase Matzel and others whole rock Washington TP1 91.83 91.95 91.71 47.9644 -120.9579 0.01 Tenpeak pluton tonalite plutonic sheeted complex Matzel and others whole rock Washington TP29 91.28 91.37 91.19 48.0077 -120.9542 0.01 Tenpeak pluton tonalite plutonic Flaser Gneiss Matzel and others whole rock Washington TP27 90.62 90.68 90.56 48.1116 -121.092 0.01 Tenpeak pluton tonalite plutonic Matzel and others whole rock Washington TP524-1 89.69 89.82 89.56 48.025 -121.023 0.01 Tenpeak pluton tonalite plutonic Indian Creek phase Matzel and others whole rock Washington Method Data 1 U-PB6:ZIRC 346 2 REG 2006-091383